Portable navigation devices (PNDs) including GPS (Global Positioning System) signal reception and processing means are well known and are widely employed as in-car navigation systems. In essence, modern PNDs comprise:                a processor,        memory (both volatile and non-volatile),        map data stored within said memory,        a software operating system and one or more additional programs executing thereon to control the functionality of the device and provide various features,        a GPS antenna by which satellite-broadcast signals including location data can be received and subsequently processed to determine a current location of the device,        input and output means, examples including a visual display (which may be touch sensitive to allow for user input), one or more physical buttons to control on/off operation or other features of the device, a speaker for audible output,        one or more physical connectors by means of which power and optionally one or more data signals can be transmitted to and received from the device, and        optionally one or more wireless transmitters/receivers to allow communication over mobile telecommunications and other signal and data networks, for example Wi-Fi, Wi-Max GSM and the like.        
The utility of the PND is manifested primarily in its ability to determine a route between start or current location and a destination, which can be input by a user of the computing device, by any of a wide variety of different methods, for example by postcode, street name and number, and previously stored well known, favourite or recently visited destinations. Typically, the PND is enabled by software for computing a “best” or “optimum” route between the start and destination address locations from the map data. A “best” or “optimum” route is determined on the basis of predetermined criteria and need not necessarily be the fastest or shortest route. The selection of the route along which to guide the driver can be very sophisticated, and the selected route may take into account existing and predicted traffic and road conditions, historical information about road speeds, and the driver's own preferences for the factors determining road choice. In addition, the device may continually monitor road and traffic conditions, and offer to or choose to change the route over which the remainder of the journey is to be made due to changed conditions. Real time traffic monitoring systems, based on various technologies (e.g. mobile phone calls, fixed cameras, GPS fleet tracking) are being used to identify traffic delays and to feed the information into notification systems.
The navigation device may typically be mounted on the dashboard of a vehicle, but may also be formed as part of an on-board computer of the vehicle or car radio. The navigation device may also be (part of) a hand-held system, such as a PDA (Personal Navigation Device) a media player, a mobile phone or the like, and in these cases, the normal functionality of the hand-held system is extended by means of the installation of software on the device to perform both route calculation and guidance along a calculated route. In any event, once a route has been calculated, the user interacts with the navigation device to select the desired calculated route, optionally from a list of proposed routes. Optionally, the user may intervene in, or guide the route selection process, for example by specifying that certain routes, roads, locations or criteria are to be avoided or are mandatory for a particular journey. The route calculation aspect of the PND forms one primary function provided, and the navigation along such a route is another primary7 function. During navigation along a calculated route, the PND provides visual and/or audible instructions to guide the user along a chosen route to the end of that route, that is the desired destination. It is usual for PNDs to display map information on-screen during the navigation, such information regularly being updated on-screen so that the map information displayed is pertinent to the current location of the device, and thus of the user or user's vehicle if the device is being used for in-car navigation. An icon displayed on-screen typically denotes the current device location, and is centred with the map information of current and surrounding roads and other map features being also displayed. Additionally, navigation information may be displayed, optionally in a status bar above, below or to one side of the displayed map information, examples of navigation information including the distance to the next deviation from the current road required to be taken by the user, the nature of that deviation possibly being represented by a further icon suggestive of the particular type of deviation, for example a left or right turn. The navigation function also determines the content, duration and timing of audible instructions by means of which the user can be guided along the route. As can be appreciated a simple instruction such as “turn left in 100 m” requires significant processing and analysis. As previously mentioned, user interaction with the device may be by a touch screen, or additionally or alternately by steering column mounted remote control, by voice activation or by any other suitable method.
A further important function provided by the device is automatic route re-calculation in the event that                a user deviates from the previously calculated route during navigation therealong,        real-time traffic conditions dictate that an alternative route would be more expedient and the device is suitably enabled to recognize such conditions automatically, or        if a user actively causes the device to perform route re-calculation for any reason.        
It is also known to allow a route to be calculated with user defined criteria; for example, the user may prefer a scenic route to be calculated by the device. The device software would then calculate various routes and weigh more favourably those that include along their route the highest number of points of interest (known as POIs) tagged as being for example of scenic beauty. Other POI-based route calculation and navigation criteria are also possible.
Although the route calculation and navigation functions are fundamental to the overall utility of PNDs, it is possible to use the device purely for information display, or “free-driving”, in which only map information relevant to the current device location is displayed, and in which no route has been calculated and no navigation is currently being performed by the device. Such a mode of operation is often applicable when the user already knows the route along which it is desired to travel.
As mentioned, PNDs may be used in a personal or business capacity, the latter use being more appropriate for commercial driving activities, such as courier and other delivery services. Additionally, where a PND is used in a car used in both a personal and business capacity, the user will typically be required, by the national government or other national authority, to keep a record of all business-only mileage for tax purposes. Additionally, for company-owned vehicles driven by one or many different company employees, the keeping of mileage records and the general use of the vehicle are important in terms of determining the overall costs and benefits provided by the vehicle to the business, and to determine the proper use thereof.
The logging of vehicle use, mileage and location information is known, and indeed well practiced commercially by companies such as Tripmaster Corp., a company which specializes in the installation of dedicated apparatus within the vehicle which communicates with other vehicle systems such as the engine and electronic vehicle management system and performs detailed logging of various engine and other vehicle use parameters. The apparatus interfaces with an on-board computer having GPS functionality to identify the exact travel of the vehicle, the various stops made and their duration, and the manner in which the vehicle made that and any journey. The apparatus requires professional installation within the vehicle in such a manner that it cannot be removed or disconnected and furthermore, the apparatus installed is highly specified in terms of memory, storage and processing capability. This therefore represents a very costly and complex solution to an intrinsically simple problem.
Additionally, U.S. Pat. No. 7,117,075 in the name of Report on Board LLC describes a method for logging and reporting driver activity and vehicle operation includes identifying a driver of a vehicle, recording operating data with an on-board recorder that is hard-wired to an engine control module, coupled to a mileage sensing system, and linked to a global navigation satellite system, and recording duty status of the driver. An hours of service log and a fuel tax log are created from the operating data. The method includes comparing the driver's hours of service log to an applicable requirement, indicating to the driver whether the driver is in-compliance or out-of-compliance with the applicable requirement, automatically uploading the logs to a receiver external to the vehicle using a wireless telecommunications network, and emitting a compliance signal representative of whether the driver is in-compliance or out-of-compliance with the applicable requirement to a second receiver external to the vehicle and under control of authorities. Again, this is a complex and costly solution.
In the case of PNDs, the storage and processing power are limited as the device size and weight are very important factors in the overall utility, portability and desirability thereof. Accordingly, the logging of large amounts of position and time data, for example by logging position and time data repeatedly and periodically every few seconds, is not practical or indeed possible, nor is the processing or formatting of such data in a useful manner.
It is an object of this invention to provide a useful logging and tracking function for PNDs, to provide a logging strategy for PNDs, and to provide a PND so enabled.